My talk given on Oct 2 2010 at JRubyConf.

1. Extending JRuby
JRubyConf 2010
Jeremy Hinegardner

2. All Work
Collective Intellect

3. All Play
github.com/copiousfreetime

4. Dull Boy
@copiousfreetime

5. Extensions

6. Ruby
Program

7. Ruby
Program
Some
Awesome
Library
sal.{dll,so,jar}

8. Ruby
Program
Ruby
Runtime
Some
Awesome
Library
sal.{dll,so,jar}

9. Ruby
Program
Ruby
Runtime
Extension
API Some
Awesome
Library
sal.{dll,so,jar}

10. Ruby
Program
Ruby
Runtime
Extension
Extension
API Some
Awesome
Library
sal.{dll,so,jar}

11. Hitimes

12. MRI - C Extensions

13. How Many of You Have ...
... A C Extension

14. How Many of You Have ...
USED
... A C Extension

15. How Many of You Have ...
USED
LOOKED AT THE SOURCE CODE OF
... A C Extension

16. How Many of You Have ...
USED
LOOKED AT THE SOURCE CODE OF
WRITTEN
... A C Extension

17. C Extension Trace

18. C Extension Trace
% irb
>> require 'rubygems'
>> require 'hitimes'

19. C Extension Trace
% irb
>> require 'rubygems'| grep require
% cat lib/hitimes.rb
require 'hitimes/paths'
>> require 'hitimes'
require 'hitimes/version'
require "hitimes/#{RUBY_VERSION.sub(/.d$/,'')}/hitimes_ext"
...

20. C Extension Trace
% irb
>> require 'rubygems'| grep require
% cat lib/hitimes.rb
require 'hitimes/paths'
>> require 'hitimes'
require 'hitimes/version'
require "hitimes/#{RUBY_VERSION.sub(/.d$/,'')}/hitimes_ext"
% find ./lib -type f -name 'hitimes_ext*'
... ./lib/hitimes/1.8/hitimes_ext.bundle
...

21. C Extension Trace
% irb
>> require 'rubygems'| grep require
% cat lib/hitimes.rb
require 'hitimes/paths'
>> require 'hitimes'
require 'hitimes/version'
require "hitimes/#{RUBY_VERSION.sub(/.d$/,'')}/hitimes_ext"
% find ./lib -type f -name 'hitimes_ext*'
... ./lib/hitimes/1.8/hitimes_ext.bundle
...
% cat ext/hitimes/hitimes_ext.c
void Init_hitimes_ext( )
{
mH = rb_define_module("Hitimes");
eH_Error = rb_define_class_under(mH, "Error", rb_eStandardError);
Init_hitimes_interval();
Init_hitimes_stats( );
}

22. void Init_hitimes_interval()
{
mH = rb_define_module("Hitimes");
cH_Interval = rb_define_class_under( mH, "Interval", rb_cObject );
rb_define_alloc_func( cH_Interval, hitimes_interval_alloc );
rb_define_module_function( cH_Interval, "now", hitimes_interval_now, 0 );
rb_define_module_function( cH_Interval, "measure", hitimes_interval_measure, 0 );
rb_define_method( cH_Interval, "duration", hitimes_interval_duration, 0 );
rb_define_method( cH_Interval, "duration_so_far", hitimes_interval_duration_so_far, 0);
rb_define_method( cH_Interval, "started?", hitimes_interval_started, 0 );
rb_define_method( cH_Interval, "running?", hitimes_interval_running, 0 );
rb_define_method( cH_Interval, "stopped?", hitimes_interval_stopped, 0 );
rb_define_method( cH_Interval, "start_instant", hitimes_interval_start_instant, 0 );
rb_define_method( cH_Interval, "stop_instant", hitimes_interval_stop_instant, 0 );
rb_define_method( cH_Interval, "start", hitimes_interval_start, 0);
rb_define_method( cH_Interval, "stop", hitimes_interval_stop, 0);
rb_define_method( cH_Interval, "split", hitimes_interval_split, 0);
}

23. JRuby - Java Extensions

24. _WHY?

25. _Why Not?

26. Hitimes

28. hitimes_instant_t hitimes_get_current_instant() {
LARGE_INTEGER tick;
QueryPerformanceCounter(&tick);
return (hitimes_instant_t)tick.QuadPart;
}

29. hitimes_instant_t hitimes_get_current_instant() {
LARGE_INTEGER tick;
QueryPerformanceCounter(&tick);
return (hitimes_instant_t)tick.QuadPart;
}
hitimes_instant_t hitimes_get_current_instant( ) {
Nanoseconds nano =
AbsoluteToNanoseconds( UpTime() );
return *( hitimes_instant_t *)&nano;
}

30. hitimes_instant_t hitimes_get_current_instant() {
LARGE_INTEGER tick;
QueryPerformanceCounter(&tick);
return (hitimes_instant_t)tick.QuadPart;
}
hitimes_instant_t hitimes_get_current_instant( ) {
Nanoseconds nano =
AbsoluteToNanoseconds( UpTime() );
return *( hitimes_instant_t *)&nano;
}
hitimes_instant_t hitimes_get_current_instant( ) {
clock_gettime( CLOCK_MONOTONIC,&time);
return ( ( NANOSECONDS_PER_SECOND *
(long)time.tv_sec ) + time.tv_nsec );
}

31. ?

32. System.nanoTime()

33. Java Extension Trace

34. Java Extension Trace
% irb
>> require 'rubygems'
>> require 'hitimes'

35. Java Extension Trace
% irb lib/hitimes.rb
% cat
>> require 'rubygems'
...
>> require 'hitimes'
if RUBY_PLATFORM == "java" then
require 'hitimes/hitimes'
else
...

36. Java Extension Trace
% irb lib/hitimes.rb
% cat
>> require 'rubygems'
...
>> require 'hitimes'
if RUBY_PLATFORM == "java" then
require 'hitimes/hitimes'
else find ./lib -type f -name '*.jar'
%
... ./lib/hitimes/hitimes.jar

37. Java Extension Trace
% irb lib/hitimes.rb
% cat
>> require 'rubygems'
...
>> require 'hitimes'
if RUBY_PLATFORM == "java" then
require 'hitimes/hitimes'
else find ./lib -type f -name '*.jar'
%
... ./lib/hitimes/hitimes.jar
% cat ext/java/src/hitimes/HitimesService.java
package hitimes;
[...]
import org.jruby.runtime.load.BasicLibraryService;
public class HitimesService implements BasicLibraryService {
public boolean basicLoad( final Ruby runtime ) throws IOException {
Hitimes.createHitimes( runtime );
return true;
}
}

38. package hitimes;
@JRubyModule( name = "Hitimes" )
public class Hitimes {
public static RubyModule createHitimes( Ruby runtime ) {
RubyModule mHitimes = runtime.defineModule("Hitimes");
RubyClass cStandardError = runtime.getStandardError();
RubyClass cHitimesError = mHitimes.defineClassUnder("Error", cStandardError,
cStandardError.getAllocator());
RubyClass cHitimesStats = mHitimes.defineClassUnder("Stats",
runtime.getObject(), HitimesStats.ALLOCATOR );
cHitimesStats.defineAnnotatedMethods( HitimesStats.class );
RubyClass cHitimesInterval = mHitimes.defineClassUnder("Interval",
runtime.getObject(), HitimesInterval.ALLOCATOR );
Hitimes.hitimesIntervalClass = cHitimesInterval;
cHitimesInterval.defineAnnotatedMethods( HitimesInterval.class );
return mHitimes;
}
[...]
}

39. Annotations
@JRubyClass( name = "Hitimes::Interval" )
public class HitimesInterval extends RubyObject {
...
@JRubyMethod( name = "duration", alias = { "length", "to_f",
"to_seconds" } )
public IRubyObject duration() { ... }
@JRubyMethod( name = "started?" )
public IRubyObject is_started() { ... }
@JRubyMethod( name = "now", module = true )
public static IRubyObject now( IRubyObject self ) { ... }
}

40. Annotations
@JRubyClass( name = "Hitimes::Interval" )
public class HitimesInterval extends RubyObject {
...
@JRubyMethod( name = "measure", module = true, frame = true )
public static IRubyObject measure( IRubyObject self, Block block ) {
Ruby runtime = self.getRuntime();
if ( block.isGiven() ) {
IRubyObject nil = runtime.getNil();
ThreadContext context = runtime.getCurrentContext();
[...]
interval.start();
block.yield( context, nil );
interval.stop();
return interval.duration();
} else {
throw Hitimes.newHitimesError( runtime, "No block given to Interval.measure" );
}
}
}

41. MRI - C Extension JRuby - Java Extension
require ‘hitimes/hitimes_ext require ‘hitimes/hitimes’
lib/hitimes/hitimes_ext.so lib/hitimes/hitimes.jar
public class HitimesService
implements BasicLibraryService {
void Init_hitimes_ext() public boolean basicLoad( ... ) { ... }
}
mH = rb_define_module("Hitimes"); RubyModule mHitimes = runtime.defineModule("Hitimes");
cH_Interval = rb_define_class_under( mH, "Interval", RubyClass cHitimesInterval =
rb_cObject ); mHitimes.defineClassUnder("Interval",
rb_define_alloc_func( cH_Interval, hitimes_interval_alloc ); runtime.getObject(),
HitimesInterval.ALLOCATOR );
rb_define_module_function( cH_Interval, "measure", cHitimesInterval.defineAnnotatedMethods(
HitimesInterval.class );
rb_define_method( cH_Interval,"duration", ... )
rb_define_method( cH_Interval,"started?", ... ) // Combined with the @JRubyMethod( name = ... )
rb_define_method( cH_Interval,"duration", ... ) // Annotations
...

42. JRuby - C Extensions

43. Jeremy Hinegardner
@copiousfreetime
jeremy@hinegardner.org
Thanks! http://copiousfreetime.org
http://twitter.com/jruby/team
http://github.com/copiousfreetime/hitimes - Hitimes library
http://www.serabe.com/ - several blog posts jruby extensions
http://ola-bini.blogspot.com/2006/10/jruby-tutorial-4-writing-java.html
http://github.com/jruby/jruby/blob/master/src/org/jruby/runtime/load/
LoadService.java
http://tatice.deviantart.com/ - Operating System Icons